Hitachi vMME Product Overview

vMME Product Overview

Document Number: 10-0100-082

Document Revision Number: 1.02

Document Status: Draft

Issue Date: 2015-05-19

Release Identifier 8.2

Security Status: Hitachi-CTA Confidential

Abstract:

This document provides an overview of the release 8.2 version of the Hitachi vMME product.

2015 Hitachi-CTA

All rights reserved.

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HITACHI-CTA CONFIDENTIAL: The information contained in this document is the property of Hitachi-

CTA. Except as expressly authorized in writing by Hitachi-CTA, the holder shall keep all information

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Document Status: 8.2, Draft Hitachi Proprietary and Confidential

iii

Publication History

Issue Change Summary Date

1.00 This is the initial draft version of the document. 04/24/2015

1.01 Input 8.2 feature content based on the latest FD documents. 05/04/2015

1.02 Update TS specification versions to Release 11; input feature content based on the

latest FD documents.

05/19/2015



iv

Table of Contents

1 About the Document ............................................................................................................................ 1

1.1 Purpose of the Document .......................................................................................................... 1

1.2 What is New in 8.2 Software Release........................................................................................ 1

1.3 Documentation changes ............................................................................................................ 3

1.4 Structure of this document ......................................................................................................... 3

2 Wireless Packet Network Overview..................................................................................................... 4

2.1 GPRS and UMTS network architecture ..................................................................................... 4

2.2 EPS network architecture .......................................................................................................... 6

3 Software Environment ......................................................................................................................... 9

3.1 Operating System ...................................................................................................................... 9

3.2 Application Management ........................................................................................................... 9

3.3 Time Management ................................................................................................................... 10

3.4 OAM ......................................................................................................................................... 10

4 MME/SGSN Software ........................................................................................................................ 12

4.1 Architectural Highlights ............................................................................................................ 12

4.2 Software Components ............................................................................................................. 12

4.3 Management VM ...................................................................................................................... 13

4.4 Resource Manager VM ............................................................................................................ 14

4.5 Call Processing VM .................................................................................................................. 15

4.6 Signaling VM ............................................................................................................................ 18

4.7 Data VM ................................................................................................................................... 20

4.8 Steering Load Balancer VM ..................................................................................................... 21

5 Interfaces ........................................................................................................................................... 22

5.1 Supported Interfaces ................................................................................................................ 22

5.2 Summary .................................................................................................................................. 22

6 Features and Services ....................................................................................................................... 88

6.1 Combined MME/SGSN Node .................................................................................................. 88

6.2 Mobility Management ............................................................................................................... 90

6.3 Customizable Cause Code Mapping ....................................................................................... 95

6.4 Session Management .............................................................................................................. 99

6.5 UE Security Management ........................................................................................................ 99



v

6.6 Subscriber Management ........................................................................................................ 101

6.7 User Bearer ............................................................................................................................ 106

6.8 HSPA+ Support ...................................................................................................................... 109

6.9 Direct Tunnel .......................................................................................................................... 109

6.10 Access Sharing .................................................................................................................... 110

6.11 UE Reachability Management ............................................................................................. 114

6.12 UE/MS Purge ....................................................................................................................... 114

6.13 RAN Information Management ............................................................................................ 114

6.14 DNS Support ........................................................................................................................ 115

6.15 SGW, PGW, MME, GGSN and SGSN Selection ................................................................. 117

6.16 Advanced Tracking Area Management................................................................................ 118

6.17 Session-less UE Automatic Detach ..................................................................................... 119

6.18 GGSN Black Listing ............................................................................................................. 119

6.19 Dynamic Load Status Based SGW and PGW Selection ..................................................... 119

6.20 3GPP Trace ......................................................................................................................... 119

6.21 Call Summary Log................................................................................................................ 120

6.22 Subscriber Location Notification .......................................................................................... 120

6.23 P-GW Relocation ................................................................................................................. 121

6.24 Peer node anchor point relocation ....................................................................................... 121

6.25 Accounting Service .............................................................................................................. 122

6.26 Signaling IP Traffic Management ......................................................................................... 125

6.27 1x CSFB Id to eNodeB Mapping .......................................................................................... 126

6.28 Priority Paging for Emergency 1xCSFB Call ....................................................................... 126

6.29 Multiple-SIM Sharing the Same MS-ISDN ........................................................................... 126

6.30 Diameter Based Interface Future Compatibility ................................................................... 126

6.31 Single Radio Voice Call Continuity (SRVCC) ...................................................................... 126

6.32 IMS Emergency Call ............................................................................................................ 127

6.33 VoLTE Support ..................................................................................................................... 128

6.34 Femto Cell Support .............................................................................................................. 129

6.35 Multi-SIM Support ................................................................................................................ 130

6.36 Camel Support and Enhancements ..................................................................................... 130

6.37 Sigtran Enhancements ......................................................................................................... 131

6.38 Unknown RAI Reporting ...................................................................................................... 131

6.39 Multimedia Priority Service .................................................................................................. 131



vi

6.40 HSS and PCC Based Network Provided Location Information ........................................... 132

6.41 S6d Override Support and Enhancements .......................................................................... 132

6.42 Non Responsive PGW Quarantine ...................................................................................... 132

6.43 Location Service ................................................................................................................... 133

6.44 TAC level service control ..................................................................................................... 134

7 Carrier Grade Capabilities ............................................................................................................... 135

7.1 Redundancy ........................................................................................................................... 135

7.2 Overload Control .................................................................................................................... 135

7.3 SON Support .......................................................................................................................... 136

7.4 In-service Upgrade ................................................................................................................. 137

7.5 In-service Patching................................................................................................................. 137

8 Operation, Admin and Maintenance Capabilities ............................................................................ 138

8.1 Configuration Management .................................................................................................... 138

8.2 Fault Management ................................................................................................................. 139

8.3 Performance Management .................................................................................................... 139

8.4 CLI .......................................................................................................................................... 144

9 Security Capabilities ........................................................................................................................ 145

10 Capacity ......................................................................................................................................... 146

11 Specification Compliance .............................................................................................................. 147

12 Deployment Examples ................................................................................................................... 148

12.1 Stand-alone MME for a green field LTE operator ................................................................ 148

12.2 Combined MME/SGSN for a G/U operator .......................................................................... 150

12.3 Stand-alone MME for a CDMA Operator ............................................................................. 153

12.4 Stand-alone Gn SGSN for a UMTS only operator ............................................................... 154

13 8.2 Software Release Document Map ........................................................................................... 156

14 References and Related Documents ............................................................................................ 157

14.1 Internal References .............................................................................................................. 157

14.2 External References............................................................................................................. 157

15 Glossary ......................................................................................................................................... 166



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List of Figures

Figure 1. Gn/Gp Based 3GPP Network Architecture ....................................................................... 4

Figure 2. S4-Based 3GPP Network Architecture ............................................................................. 5

Figure 3. Non-roaming architecture for 3GPP access ..................................................................... 7

Figure 4. Roaming architecture for 3GPP access ............................................................................ 7

Figure 5. Protocol Stack for S1 Interface for Control Plane ........................................................... 24

Figure 6. Protocol Stack for S3 and other Mobility Management interfaces .................................. 28

Figure 7. Protocol stack for S4 interface and other Session Management interfaces ................... 30

Figure 8. Protocol stack for S4 user plane interface ...................................................................... 32

Figure 9. Protocol Stack for S6 interface ........................................................................................ 33

Figure 10. Protocol stack for S11 interface ...................................................................................... 36

Figure 11. Protocol Stack for S13 interface ...................................................................................... 38

Figure 12. Protocol stack for S101 interface .................................................................................... 41

Figure 13. Protocol stack for S102 interface .................................................................................... 42

Figure 14. Protocol Stack for CBC eNB ........................................................................................ 43

Figure 15. Protocol Stack for SGs interface ..................................................................................... 44

Figure 16. Protocol stack for Sv interface ........................................................................................ 46

Figure 17. Protocol Stack for SLg interface ...................................................................................... 47

Figure 18. Protocol Stack for SLs interface ...................................................................................... 48

Figure 19. Protocol Stack for Fxa interface ...................................................................................... 49

Figure 20. Protocol stack for Ga interface ........................................................................................ 50

Figure 21. Protocol stack for Gb interface (IP based transport) ....................................................... 51

Figure 22. Protocol Stack for Gb User Bearer Plane ....................................................................... 55

Figure 23. Protocol Stack for Gd interface ....................................................................................... 57

Figure 24. Protocol Stack for Ge interface ....................................................................................... 61

Figure 25. Protocol Stack for Gf interface ........................................................................................ 63



viii

Figure 26. Protocol Stack for GTP-U ................................................................................................ 66

Figure 27. Protocol Stack for Gr interface ........................................................................................ 67

Figure 28. Protocol Stack for Gs interface ....................................................................................... 69

Figure 29. Protocol Stack for Iu User Bearer Plane Anchored on the SGSN ............................... 71

Figure 30. Protocol Stack for Iu User Bearer Plane Direct Tunnel ............................................... 71

Figure 31. Protocol Stack for Iu User Bearer Plane S4-SGSN case ............................................ 72

Figure 32. Protocol Stack for Iu Control Plane ................................................................................. 73

Figure 33. Protocol Stack for Control Plane for UE - MME .............................................................. 78

Figure 34. Protocol Stack for Control Plane MS SGSN in A/Gb Mode ......................................... 82

Figure 35. Protocol Stack for Control Plane MS SGSN in Iu Mode .............................................. 82

Figure 36. Protocol Stack for X interface between the MME and the LIG ....................................... 84

Figure 37. Protocol Stack for HI2 ..................................................................................................... 86

Figure 38. Protocol Stack for Domain Name Service interface ........................................................ 86

Figure 39. Combined MME/SGSN in a wireless network with 2G/3G/4G access technologies ...... 89

Figure 40. National roaming network Example .............................................................................. 104

Figure 41. Deployment example 1 Network Level View ............................................................ 149

Figure 42. Deployment example 1 Nodal level view .................................................................. 150






ix

List of Tables

Table 1. vMME Application Software Composition ........................................................................... 13

Table 2. Logical Interfaces ................................................................................................................ 22

Table 3. S1-AP Messages................................................................................................................. 24

Table 4. S3 Interface Messages ....................................................................................................... 28

Table 5. S4 interface GTP-C Messages ........................................................................................... 30

Table 6. S4 User Bearer Plane Messages ........................................................................................ 32

Table 7. S6 Messages ....................................................................................................................... 33

Table 8. S10 Messages ..................................................................................................................... 34

Table 9. S11 interface Messages ...................................................................................................... 36

Table 10. S13 Messages ................................................................................................................. 39

Table 11. S16 Messages ................................................................................................................. 39

Table 12. S101 Interfaces Messages .............................................................................................. 41

Table 13. S102 Interface Messages ............................................................................................... 42

Table 14. SBc Interface Messages ................................................................................................. 43

Table 15. SGs Interface Messages ................................................................................................. 44

Table 16. Sv Interface Messages .................................................................................................... 46

Table 17. SLg Interface Messages ................................................................................................. 47

Table 18. SLs Interface Messages .................................................................................................. 48

Table 19. Fxa Interface Messages .................................................................................................. 49

Table 20. Ga Interface Messages ................................................................................................... 50

Table 21. Gb NS messages ............................................................................................................ 52

Table 22. Gb IP Sub-Network Service Control messages .............................................................. 52

Table 23. Gb BSSGP messages ..................................................................................................... 53

Table 24. SNDCP Messages .......................................................................................................... 55

Table 25. LLC Messages ................................................................................................................ 56



x

Table 26. Gd Messages .................................................................................................................. 57

Table 27. M3UA Layer Messages ................................................................................................... 58

Table 28. SCCP Layer Messages ................................................................................................... 59

Table 29. TCAP Layer Messages ................................................................................................... 59

Table 30. Ge Interface messages ................................................................................................... 61

Table 31. Gf Messages ................................................................................................................... 63

Table 32. Gn/Gp Interface Mobility Management Messages .......................................................... 64

Table 33. Gn/Gp Interface Session Management Messages ......................................................... 64

Table 34. Gn/Gp Interface User Bearer Plane Messages .............................................................. 66

Table 35. Gr Messages ................................................................................................................... 67

Table 36. Gs Messages .................................................................................................................. 69

Table 37. Iu Messages .................................................................................................................... 73

Table 38. SCCP Layer Messages ................................................................................................... 76

Table 39. M3UA Layer Messages ................................................................................................... 77

Table 40. NAS Evolved Mobility Management Messages .............................................................. 79

Table 41. Evolved Session Management messages ...................................................................... 80

Table 42. NAS GPRS Mobility Management Messages ................................................................. 83

Table 43. Session Management messages .................................................................................... 83

Table 44. X Interface Messages ..................................................................................................... 85

Table 45. Mobility Scenarios Supported ......................................................................................... 91

Table 46. DNS Procedure and service parameter usage ............................................................. 115

Table 47. 3GPP Technical Specifications ..................................................................................... 122

Table 48. Group Sets and Groups ................................................................................................ 139

Table 49. System Capacity and Performance............................................................................... 146

Table 50. Per Subscriber Capacity ............................................................................................... 146

Table 51. Documentation Map ...................................................................................................... 156

Table 52. External References and Related Documents (3GPP) ................................................. 157



xi

Table 53. External References and Related Documents (3GPP2) ............................................... 164

Table 54. External References and Related Documents (IETF)................................................... 164



1

1 About the Document

1.1 Purpose of the Document

This document presents the technical information regarding the virtualized combined MME/SGSN

node. The technical detail includes functions and capabilities implemented up to the 8.2 Release.

With virtualization complete, the combined MME/SGSN node is no longer confined to the computing

power of a physical chassis or a frame.

This product can be deployed as a combined MME/SGSN node. In addition, it can also be deployed

as a standalone MME, or a standalone SGSN, depending on the needs of the wireless network

operator. For operators that are currently using earlier releases on Advanced Telecom Computing

Architecture (ATCA) platform, the vMME can be introduced to the MME/SGSN pool and gradually

phase out the ATCA based nodes.

The term vMME in this document refers to the product as a whole, which includes both the MME

function and the SGSN function. When the term MME is used alone, it means the MME function of

the vMME whether it is a standalone MME or part of a combined MME/SGSN. When the term

SGSN is used, it means the SGSN function of the vMME whether it is a standalone SGSN or part of

a combined MME/SGSN. The term S4-SGSN refers to one configuration of the SGSN function that

utilizes the S4 interface for session management. The term Gn-SGSN refers to one configuration of

the SGSN function that utilizes the Gn interface for session management. The SGSN can

simultaneously support Gn-SGSN and S4-SGSN capability.

1.2 What is New in 8.2 Software Release

The following features/functionalities are added in this release:

AGW-21835 Proprietary RAN and NAS cause code to SGW This feature enables the MME to

support the inclusion of RAN/NAS causes in S11 messages: Delete Session Request and Delete

Bearer Command

AGW-23552 EMBMS - This feature implements the Multimedia Broadcast and Multicast Service

(MBMS) specified in TS 23.246 on the MME. MBMS is a point-to-multipoint service which data is

transmitted from a single source entity to multiple recipients. Multiple subscribers can receive the

same data at the same time on the same frequency.

AGW-24378 CLI Initiated Explicit Detach This feature allows the operator to choose the detach

type (implicit or explicit) when clearing the subscriber. Previous functionality performed an implicit

detach.

AGW-24908 MME Collision With this feature, the MME is enhanced to provide the following

collision handling:

About the Document



2

An enhanced Mobility Management (eMM) procedure (except network initiated Detach)

suspended due to handover (HO) is implicitly completed if the X2 or S1 HO indicates a

Tracking Area Identity (TAI) change.

Radio Link Failure (RLF): When eNodeB (eNB) sends UE Context Release Request with

cause Radio Connection with UE lost during HO, the MME aborts any suspended eMM

and/or enhanced Session Management (eSM) procedures, aborts the HO and releases

all S1 connections. During HO, if the MME receives a UE initiated procedure on a new S1

connection due to RLF, the MME aborts any suspended eMM and/or eSM procedures,

aborts the HO, releases all old S1 connections and processes the UE initiated procedure.

If another X2 or S1 HO request is received while the MME is waiting for the handover-

resource-release-timer to expire or in the middle of cleaning up sessions from the source

Serving Gateway (S-GW) due to S-GW relocation, the new HO request is buffered until

the MME completes cleaning up the sessions on the source S-GW.

UE is implicitly detached by MME when an expected Tracking Area Update (TAU)

Request after HO is not received.

For Mobile Terminated (MT) Circuit Switched Fallback (CSFB) in ECM-Active mode, the

Non-Access Stratum (NAS) CS Service Notification message is queued when MME

receives NAS Non Delivery Indication from the eNB indicating the NAS message is not

delivered due to HO in progress. After HO completes, the MME resends the NAS CS

Service Notification message to the UE.

Home Subscriber Server (HSS) initiated T-ADS Retrieval via Insert-Subscriber-Data-

Request (IDR) is immediately processed by the MME even if the MME is in the middle of

paging, handover or an eMM procedure. The last known TAI for the UE is used to provide

information such as VoLTE support in the Insert-Subscriber-Data-Answer (IDA) message

to the HSS.

AGW-25446 MME 3GPP Interfaces to Release 11 - The MME interfaces are upgraded to be

compliant to the September 2014 version of the Release 11 specifications. Further, for each

interface, an attribute is added to allow the operator to control the version of the interface used by

the node. The operator can use the latest version when the related network nodes are ready to

utilize the new version of the related protocols.

AGW-25498 CLI Ping through Routing Instance This feature provides a CLI command to ping

adjacent 3GPP nodes (an eNodeB) using a configured 3GPP source IP (s1 interface address)

through an LB VM.

AGW-25809 MME LCS Emergency Service Enhancement - This feature enhances the MME

Location Service (LCS) functionality for the emergency. The enhancements are categorized into

configuration, counters, messages and new supported functionality for LCS.

AGW-25811 Inter PLMN Roaming Restriction - This feature enables the network operator to

restrict idle mode inter-node inter-PLMN TAU procedure. The operators are given the ability to

reject or allow the idle mode inter-node inter-PLMN TAU procedure based on the source PLMN

derived from the old GUTI in the TAU request.

About the Document



3

AGW-25814 GW Blacklisting Enhancements - This feature allows the operator to manually

blacklist SGWs and PGWs and improves the GW selection process by dynamically detecting

failed SGW and PGW.

1.3 Documentation changes

None in this release.

1.4 Structure of this document

The Hitachi vMME is the ultimate mobility management product for the wireless packet network. Its

capabilities span the Evolved Packet System (EPS); aka, 4G networks, as well as the widely

deployed GPRS (2G) and UMTS (3G) packet networks. The rest of the document presents the

capabilities and functions of the vMME.

Wireless Packet Network Overview provides an overview of the wireless packet network from the

standards point of view. Readers familiar with reference network architecture as defined by the 3GPP

standards body should already be familiar with the content of this chapter.

Software Environment provides an overview of the software Environment.

MME/SGSN Software discusses the MME/SGSN software.

Interfaces covers the supported logical interfaces, including both 3GPP defined interfaces and a few

proprietary interfaces.

Features and Services details the features and services provided by the vMME. This chapter also

showcases a rich set of value-add features available on the node. Many of the features are unique in

the industry. Carrier grade capabilities are one of the key differentiators of the vMME and are detailed

within this chapter. To enable ease of use, the vMME also boasts a rich set of OAM capabilities. A

highlight of the key functions is described. To ensure both nodal and end user security, the vMME

supports both network domain and user domain security. The chapter ends with a description of the

capacity and performance of the vMME.

Deployment Examples showcases a few possible network level use cases and related configurations.

This helps the network operators better understand how the vMME can be integrated smoothly into

their networks.

8.2 Software Release Document Map provides a document map for the other documents available to

our customers for this release.



4

2 Wireless Packet Network Overview

2.1 GPRS and UMTS network architecture

Prior to the publication of release 8 specifications by 3GPP standards body, the General Packet

Radio Service is a second generation (2G) wireless standard based on a GSM access network and

MAP (Mobile Application Part) core. The Universal Mobile Telecommunications System is a third

generation (3G) wireless standard based on a Code Division Multiple Access (CDMA) access

network and a MAP core.

Since release 8, the traditional network architecture is now referred to Gn/Gp based network whereas

the new network architecture is referred to as S4-based architecture. The following figure shows the

Gn/Gp based architecture as defined by 3GPP specification TS 23.060.

Figure 1. Gn/Gp Based 3GPP Network Architecture

Gf

Uu

Um

D

Gi

Gn

Iu

Gc

C E

Gp

Gs

Signalling Interface (including SMS) Signalling and Data Transfer Interface

TE MT UTRAN TE PDN

Gr Iu

Other PLMN

Gd

SMS-SC SMS-GMSC SMS-IWMSC

GGSN

EIR SGSN

Gn CGF

Ga Ga

Billing

System

Gb

TE MT BSS

R

A

R

gsmSCF

Ge

SGSN

HLR MSC/VLR

GGSN

As part of the release 8 specification, the core network has evolved to be a mixture of MAP and

Diameter core. Further, the wireless architecture is gradually evolving towards a unified packet core

that is embodied in the EPC network architecture discussed in the next section. The R8 based 2G/3G

packet network is referred as the S4-based network.

Wireless Packet Network Overview



5

Figure 2. S4-Based 3GPP Network Architecture

S13

Uu

Um

D

SGi

S4

Iu

C E

S8

Gs

Signalling Interface (including SMS) Signalling and Data Transfer Interface

MSC/VLR

TE MT UTRAN TE PDN

S6d/Gr (see Note) Iu

HSS

Other PLMN

SGSN

Gd

SMS-SC SMS-GMSC SMS-IWMSC

EIR SGSN

S16

Gb

TE MT BSS

R

A

R

gsmSCF

Ge

P-GW

S-GW

S5

S12

P-GW

In this section we will provide basic introduction to the interfaces that are relevant to the SGSN. The

readers are referred to the 3GPP specifications (mainly TS23.060) for a full discussion of each node

in the network architecture and its interfaces. See section External References.

Regardless of the architecture flavor, the interfaces from the core to the access nodes remain the

same. For the 2G network, the interface between the SGSN and the Access node is the Gb interface.

For the 3G network, the interface between the SGSN and the Access node is the Iu interface. The

interfaces used to bridge the packet network and circuit network are also the same. Additionally,

some SS7 based interfaces remain:

Gs: Interface between the SGSN and MSC/VLR for combined attached subscribers.

Gd: Interface between the SGSN and the SMS Gateway MSC for SMS delivery for the Short

Message Center.

Ge: Interface between the SGSN and the SCF to control UEs usage of the packet network. It is

typically used for prepaid data services.

The interfaces between the packet core nodes have changed from the Gn/Gp based architecture to

S4 based architecture.




6

Gn: Interface between the SGSN and GGSN for user session management as well as between

two SGSNs for user mobility management. Another flavor for Gn is Gp, which is the same

interface but between networks belonging to two operators.

S4: Interface between the SGSN and the SGW for session management. S4 supersedes the

session management aspect of the Gn interface when a network moves from Gn/Gp based

architecture to S4 based architecture.

S16: Interface between two SGSNs for user mobility management, replacing the mobility

management aspect of the Gn interface.

Gr: Interface between the SGSN and the HLR for authentication information and subscription

information management.

S6d: Interface in the S4-based architecture between SGSN and the HSS for authentication

information and subscription information management. This interface supersedes the Gr

interface.

Ga: Interface between the SGSN and the CGF for SGSN Accounting.

Gf: Interface between the SGSN and the EIR for equipment validation.

S13: Interface between the SGSN and the EIR for equipment validation. S13 interface replaces

Gf interface in the S4 based 3GPP Network Architecture.

2.2 EPS network architecture

The EPS network evolves from the GPRS and UMTS network. There are a few major changes

compared to the GPRS and UMTS network:

All IP based infra-structure: Not only is the interface between the access nodes and the core

nodes IP based, the interfaces between the core nodes are also all IP based. The Diameter

based protocol replaces MAP based interfaces.

No more circuit domain: Unlike the 2G and 3G network, the 4G EPS network no longer has a

circuit domain that used to provide parallel mobility management for the UEs. Voice services are

achieved using either: IMS (VoLTE) or CS Fallback (SGs).

The following figures show the network architecture as defined by TS 23.401.




7

Figure 3. Non-roaming architecture for 3GPP access

SGi

S12

S3

S1-MME

PCRF

Gx

S6a

HSS

Operator's IP Services

(e.g. IMS, PSS etc.)

Rx

S10

UE

SGSN

LTE-Uu

E-UTRAN

MME

S11

S5 Serving Gateway

PDN Gateway

S1-U

S4

UTRAN

GERAN

Figure 4. Roaming architecture for 3GPP access

The following interfaces are related to the MME:

S1-MME: Interface used to connect the E-UTRAN access nodes to the MME for signaling. The data

plane interface is the S1-U between the access nodes to the Serving Gateway.

S3: Interface between the MME and the S4-SGSN for mobility management purpose.

S6a: Interface between the MME and the HSS for subscription and authentication information

management.

S6a

HSS

S8

S3

S1 - MME

S10

UTRAN

GERAN

SGSN

MME

S11

Serving

Gateway UE

LTE - Uu

E - UTRAN

S12

HPLMN

VPLMN

PCRF

Gx Rx

SGi Operators IP Services

(e.g. IMS, PSS etc.)

PDN

Gateway

S 1 - U

S4




8

S10: Interface between two MME nodes for inter-MME mobility management.

S11: Interface between the MME and the S-GW for PDN and bearer management. The S-GW

extends the signaling from the MME to the PGW via the S5 or S8 interface.

The readers are referred to TS23.401 for more details on the other interfaces mentioned in the figures

above. Please note, EPC network architecture figures in this section do not cover all the interfaces.

For example, the SGs interface between the MME and the VLR/MSC. This interface allows UE in the

4G network to fall back to 2G GSM or 3G UMTS network for voice call. Another interface not depicted

here is the S13 interface between the MME and the EIR for equipment validation.

In addition to the interfaces discussed above, the vMME also supports other interfaces used to bridge

the existing CDMA 1xRTT network with the 4G E-UTRAN network:

S101: Interface between the HRPD access nodes with the MME to facilitate mobility between the

E-UTRAN network and the HRPD network.

S102: Interface between the MME and the InterWorking System (IWS) to facilitate falling back to

the 1xRTT circuit domain for voice call.



9

3 Software Environment

The vMME adopts layered software architecture. From a high level, the system can be divided into

three layers1.

The operating system layer

Platform services (also referred to as middleware) layer

The application layer

This section delves into the function and capability of the Operating System layer and Platform

Services layer. The application layer is detailed in the next section.

3.1 Operating System

The vMME virtual machines run the Linux operating system. The Linux OS is based on the Ubuntu

12.04.2 LTS server distribution, with customization to remove un-needed software. The Linux kernel

from Ubuntu has been optimized to run in the virtual environment, and configured to exclude options

and functions that are not needed. Carrier grade extensions developed by Hitachi are incorporated to

enable the high availability application environment and tools necessary to meet Hitachis stringent

reliability requirements.

The same operating system runs on every virtual machine of the system.

3.2 Application Management

The vMME software is partitioned into several types of virtual machines. One of the virtual machine is

the management VM (or MGMT VM), which is responsible for the Operations, Administration and

Maintenance of a logical vMME node. The six types of virtual machines of the vMME are:

MGMT (OAM)

RM (resource management)

CALLP (call processing, control plane)

DATA (data plane for SGSN)

1 For a virtualized environment, there are other layers of software to support and orchestrate the virtualized

machines. We will not discuss details of that layer of software in this document.

Software Environment



10

SIG (signaling)

SLB (steering load balancer)

The Application Management software is part of the platform middleware that runs mainly on the

MGMT VM, with local agent on every VM. The Application Management software manages the

lifecycle of application software installed on the system. It is responsible to control the start, stop,

switch of activity of application software entities. Further, it performs monitoring of the application

software to ensure they are running properly.

There can be multiple instances of a VM type. For a given VM type, the redundancy scheme is fixed.

Two types of redundancy schemes are used by the vMME. One is 1:1 active/standby synchronized

redundancy, the other is N-way load shared redundancy. For 1:1 spared VMs such as CALLP and

MGMT, there are up to two units in a VM service pair. For N-way load shared VMs such as DATA, all

the VMs are active while the collection is engineered at capacity and performance of N-1 instances. If

one VM fails, the remaining N-1 VMs are able to take over the capacity without exceeding

engineering limit on each VM.

Each VM contains an aggregation of software functions where each software function represents a

running software resource, for example, a set of processes.

A comprehensive set of CLI commands are supported to allow the operator to configure and manage

the VMs required for a particular vMME.

3.3 Time Management

The vMME uses Network Time Protocol (NTP) to manage time both across the network and within

the system. It is imperative to configure at least one NTP server to ensure that all the nodes in the

network to have synchronized timestamps for all events generated, including charging, fault reporting

etc.

3.4 OAM

For Operations, Administration and Maintenance, the vMME (mme-sgsn) provides the following

functions and northbound interfaces to an NMS (Network Management System):

CM (Configuration Management):

All semantic rules run on the MGMT VM prior to commit

Supports connections via IETF NETCONF

CLI (Command Line Interface): SSH and local serial console

Multiple concurrent CLI and NETCONF sessions are supported

Software Environment



11

Hierarchical organization of commands and config

Tab based auto-completion and short form on-line help

PM (Performance Management):

One file per node per collection interval

Collection intervals: 5, 15, 30 minutes

CLI access cumulative registers

SFTP pull via external IP address of MGMT VM

Format: 3GPP XML - per 3GPP Technical Specifications: 32.401, 32.404, 32.406,

32.426, 32.432, 32.425

FM (Fault Management):

Customer logs and alarms available by IETF RFC-5424 compliant syslog

Supports SNMPV2 (MIB and OpenNMS eventconf.xml files provided for MME/SGSN)

SNMP and syslog streams presented to NMS via OAM interface of MGMT VM

CSL (Call Summary Log):

One binary file per node per collection interval

SFTP pull of output file via external IP of MGMT VM

Off-board SCTP streaming mode available, recommended for large systems

Captures configurable call release events per UE including

Category: failure, reject, release (abnormal and normal releases), success

Units: mobility, bearer, PDN, radio bearer

TRACE:

Up to ten UE may be configured persistently per: IMSI, IMEI, or MSISDN

One XML file per UE session

SFTP pull of output file via external IP of MGMT VM

Implemented per 3GPP technical specifications: 32.421/422/423



12

4 MME/SGSN Software

The vMME software traces its origin back in late 1990s when the GPRS SGSN was first developed.

By the year 2000, the UMTS SGSN completed development and was being deployed in customer

networks worldwide shortly thereafter. With the support for LTE being defined by the 3GPP

organization, our vision for LTE has been to leverage the field-tested and successful SGSN software

base combined with support for MME utilizing common procedures wherever possible. With MME 6.0,

the product can be deployed to customer networks in a combined MME/SGSN configuration, allowing

Operators to reduce operational and capital expenditures by providing high-capacity LTE solutions

while at the same time allowing the same node to manage the 2G and 3G access networks. The

previous release introduced the virtualization technology to the combined MME/SGSN, where the

MME/SGSN is no longer confined to the physical limitations of a chassis.

4.1 Architectural Highlights

The vMME follows the following architectural principle in developing a highly reliable carrier grade

core node:

No single point of failure: From the hardware to platform software to the application software,

redundancy is innate to the design. The system continues to maintain normal service even if there is

a single fault on the system. Furthermore, mobile users that have already attached to the node are

not impacted and continue to receive service.

IP Address efficiency: Despite the high capacity of the vMME, the IP address consumption is at

minimum. Packet steering technology is used within the system to ensure the same IP address can

be serviced by multiple VMs across multiple compute nodes.

Separation of Data and Control: To ensure independent scaling of the signaling load and user bearer

load, the vMME separates control plane software and data plane software on two different sets of

VMs. This ensures CPU resource between the control plane and data plane is properly fenced.

Independent scaling of subscriber capacity and access node connection capacity: The subscriber

capacity and the access node connection capacity are two competing requirements on an MME or an

SGSN. To allow the maximum flexibility, the vMME allows scaling of the two requirements

independently.

4.2 Software Components

The vMME software is grouped based on its function into six different types of virtual machines. Each

virtual machine represents an instance of Linux Operating System running on a compute node that

has a host operating system and a hypervisor. There can be more than one virtual machine on a

single compute node.

MME/SGSN Software



13

4.2.1 Summary

The details of each type of virtual machine are examined in the ensuing sections. In this section we

provide a tabular view of all the different types that can be configured.

Table 1. vMME Application Software Composition

VM Type Function Max number

of Active per

System

Max total

number per

System

Used by

MME

Used by

S4-

SGSN

Used by

Gn-

SGSN

Management Operations,

Administration and

Maintenance

1 2 Yes Yes Yes

Resource

Manager

Application layer

resource management

1 2 Yes Yes Yes

Call

Processing

Subscriber Control

function

112 22 Yes Yes Yes

Signaling Termination of logical

interfaces

2 20 Yes Yes Yes

Data Handling of user data

plane

15 15 Yes Yes

Steering

Load

Balancer

Handling control plane

IP packet steering

2 8 Yes Yes Yes

For a node that is deployed to support multiple functions, all the required virtual machine types should

be configured. For example, a combined MME/SGSN node that supports both S4-SGSN and Gn-

SGSN capability should have all the VM types present in the system.

4.3 Management VM

The Management VM is the center of Operations, Administration and Maintenance for the vMME. It

runs in 1:1 active/standby mode. It hosts software functions that perform configuration management

of the vMME, collect performance data from the application layer, monitor faults and process status

queries from the operator or the north-bound element manager.

Only one active instance of Management VM and one standby is required.

2 One instance is deployed for Diameter Client use only if the operator wants to use single Diameter instance.

MME/SGSN Software



14

On top of the above mentioned standard OA&M functions, the Management VM also hosts a couple

of data collection applications. One is the collector for the Call Summary Logs that are generated as

the result of call processing; the other is the collector for the 3GPP Trace data when the activities of

traced subscribers are captured.

4.4 Resource Manager VM

The Resource Manager VM is responsible for managing the application layer resources. It also hosts

single active instance applications on the vMME. The following software functions can be instantiated

on the Resource Manager VM.

4.4.1 Resource Manager

The Resource Manager (RM) manages the global resources of the vMME, which is built on a

distributed virtualized environment. It enables multi-dimensional scaling of subscriber count, access

fan-out and user data throughput. The application software, such as the Subscriber Control in the

CallP VM, needs the resources to manage a slice of the subscribers on the vMME. The Resource

Manager ensures that system resources are utilized to their maximum extent without collision

between the applications on various virtual machines. The Resource Manager is also responsible for

the load-balancing within the cluster of VMs that form one vMME node.

4.4.2 SBc

The MME supports the SBc interface to start, stop and receive Public Warning System (PWS) and

Commercial Mobile Alert System (CMAS) messages from the CBC, and broadcast the message to all

the eNodeBs in the tracking area designated by the CBC. The SBc interface uses the SBc

Application protocol and SCTP as the message transport. The SBc function is responsible for the

following functions:

Maintain up to four SCTP connections to the CBC

Encode/Decode SBc-AP layer messages

Deliver the warning message to the eNodeB with highest priority

Notify the CBC about the message delivery. The response to CBC will not wait for eNodeBs

response to MME

Support redundancy in case of blade failure

Ability to start and stop the broadcasting of PWS and CMAS messages

MME/SGSN Software



15

The instantiation of SBc function depends on if the operator requires the use of the SBc interface for

emergency broadcasting purpose. If the interface is configured, the vMME instantiates the SBc

function on the Resource Manager VM.

4.4.3 LI

The LI function is used to provide Legal Interception (LI) capability to the vMME. It maintains

connection to the Legal Intercept Gateway which directs the MME/SGSN on the monitoring

information.

The LI function supports the reporting of activity of the UE, known as Intercept-Related Information, or

IRI to the Legal Intercept Gateway (LIG). In the case when user bearer is also established on the

node (SGSN with 2G subscribers, or non-direct tunnel 3G subscribers), the LI function can also report

the communication content of the UE to the LIG if requested.

The LI function is only instantiated if Legal Intercept interface is required and configured on the

vMME.

4.4.4 Ga

The Ga function is used for the SGSN to transfer charging records to the Charging Gateway Function

via the Ga interface. It can also store the charging records locally on the file system for retrieval. The

SGSN can be configured to generate M-CDRs for mobility related records, S-CDR for session related

records and SMS-CDRs for short message service related records. The generated CDR records are

transferred to the CGFs. If the CGFs are down, the records are spooled in the local disk. The spooled

records are replicated on the standby Resource Manager VM.

The Ga function is only instantiated on the Resource Manager VM when the Ga interface is

configured on the vMME.

4.5 Call Processing VM

The Call Processing VM is the signaling processing center of the vMME. It runs in 1:1 active/standby

mode. The key function of the Call Processing VM is subscriber management.

Each vMME can have multiple pairs of Call Processing VMs running in 1:1 spared mode. The

capacity of the vMME grows with the number of Call Processing VMs configured.

The following functions are hosted on the Call Processing VM.

MME/SGSN Software



16

4.5.1 Subscriber Control

The Subscriber Control (SC) is responsible for processing signaling for the UE, regardless whether it

is originated by the UE or initiated by a network node. The Subscriber Control is the processing

engine for all UE related messages.

The following functions are provided by the Subscriber Control:

Mobility Management

Session Management

Layer 2 Mobility management for optimized active mode handover

The SC process is responsible for handling user signaling. The SC also handles commands received

from the OAM interface, and the CLI interface.

At least one Call Processing VM pair should be deployed on the vMME. For higher subscriber

capacity, more Call Processing VMs can be deployed (up to ten pairs3). Each VM pair is deployed in

1:1 redundancy scheme on two different compute nodes.

4.5.2 Diameter Client

The MME and S4-SGSN utilize the Diameter Clients configured on the MME/SGSN for the S6 (S6a

and S6d) interface, the S13 interface, as well as the SLg interface. The MME or the SGSN requests

the subscription related information via the S6 interface from the HSS. The above mentioned

interfaces use Diameter and SCTP as the message transport. The Diameter Client is responsible for

the following functions:

Maintain the SCTP connections to a set of Diameter peers

Encode/Decode S6,S13 and SLg Application layer messages

Route the messages to the correct SC process

When Diameter protocol is required for the vMME, the Diameter Client is instantiated on at least one

of the CallP VM pairs. For higher Diameter Client processing capability, multiple instances can be

deployed. At maximum, there can be a Diameter Client per CallP VM pair on the vMME.

3 One additional pair of CallP VMs can be deployed if only Diameter Client is enabled on the pair.

MME/SGSN Software



17

4.5.3 lu

The Iu function provides interface to the 3G access network, or the UTRAN. The Iu function is

responsible for the following:

terminate the RANAP and SCCP layer between the RNC and the SGSN

route the RANAP messages to the correct SC process

manage the SCCP layer connections for UE signaling

Please note, unlike the S1 function which provides connectivity to 4G access network, the Iu function

does not maintain direct SCTP association to the access network. The SCTP associations are fulfilled

by the IPSP function hosted on the Signaling VM discussed in the next section.

The Iu function is instantiated on the CallP VM if the SGSN supports 3G access technology.

4.5.4 SGs

The SGs function is used to terminate the SGs interface between the MME and the VLR. The key

functions of the SGs are:

Maintain SCTP association with the VLRs

Encode/Decode SGs-AP layer messages

Route the message to the current Subscriber Control

The SGs function can be instantiated on the CallP VM when the SGs interface is configured.

4.5.5 SLs

The SLs function is used to terminate the SLs interface between the MME and the eSMLC. The key

functions of the SLs are:

Maintain SCTP association with the eSMLCs

Encode/Decode LCS-AP layer messages

Route the message to the current Subscriber Control

The SLs function can be instantiated on the CallP VM when the SLs interface is configured.

MME/SGSN Software



18

4.6 Signaling VM

The Signaling VM is responsible for terminating the logical interfaces with an external node. All the

interfaces hosted on the Signaling VM use N-way load-sharing redundancy. As such, multiple active

instances of a signaling VM can be deployed on the vMME. The higher the number of Signaling VMs,

the higher the fan-out and signaling processing capability of the vMME.

The following functions are hosted on the Signaling VM.

4.6.1 S1

The S1 function provides interface to the 4G access network, or the E-UTRAN. The S1 is responsible

for the following:

receive and maintain SCTP connections from the eNodeBs that are in the service area of the

MME

terminate the S1-AP layer

route the S1-AP messages to the correct SC process

The instantiation of the S1 function on the Signaling VM depends on whether the vMME is used to

support 4G Access technology or not.

4.6.2 UDP Path Manager (UPM)

The UPM function is used to process all GTP-C based interfaces, as well as other UDP based

interfaces, including the following:

S11

S10

Fxa (Radius based)

S3

S4

S16

Sv

Gn/Gp

S101

S102

MME/SGSN Software



19

Details of afore-mentioned interfaces are discussed in Supported Interfaces.

The function of UPM includes:

For GTP based protocols:

GTP-Path Management

Decoding/Encoding GTP headers

Routing the GTP messages to the correct SC process

For RADIUS based protocols (Fxa):

RADIUS Fxa Path Management

Routing the messages to the correct SC process

1x CS based protocol

S102 Path Management

Relay S1AP CDMA2000 messages between the MME and IWS

Routing the messages to the correct SC process

4.6.3 TCAP

The Transaction Capabilities Application Part (TCAP) application provides a communication channel

towards an SS7-based network for a number of applications that are based on MAP.

The TCAP function supports the Gf, Gr, Ge and Gd interfaces.

The instantiation of the TCAP function depends on if SS7 signaling is used for the SGSN.

4.6.4 SIGTRAN

The SIGTRAN function (also referred to as SIGTRAN ASP or ASP) implements the M3UA layer, and

provides signaling transport over an IP network for the Gr, Gs, Gf, Ge and Gd interfaces to the HLR,

MSC/VLR, EIR, SCF and SMSC. This application provides support for both ANSI and ITU based

signaling.

Similar to TCAP, the instantiation of the SIGTRAN depends if SS7 signaling is required or not on the

vMME.

MME/SGSN Software



20

4.6.5 IPSP

The IPSP function is used to provide M3UA connectivity to the 3G access network, or the UTRAN to

support the Iu function that runs on the CallP VM. It provides the M3UA layer function for the Iu

function discussed above. The IPSP function maintains SCTP associations with the peer M3UA

based peer node. The IPSP further routes the incoming messages based on the destination point

code to the correct Iu function residing on the right CallP VM.

The instantiation of IPSP depends on whether 3G access technology is supported on the vMME or

not.

4.7 Data VM

The Data VM is used only with the SGSN function to support 2G or 3G user data packets. Multiple

active instances are configured to support the needed throughput required for the SGSN. When 2G

access technology is required, it is recommended to be configured in pairs to provide redundant

connectivity to every 2G BSS node. Otherwise, any number of active instances of Data VM can be

configured.

The following functions are hosted on the Data VM.

4.7.1 Gb

The Gb function provides the Gb interface to the 2G access network, or the GERAN. It terminates

both the BSSGP layer and NS layer towards the BSS. The SGSN IP based NS layer. It can be used

to connect to BSS nodes that support IP based Gb interface directly via an IP backbone network. The

instantiation of the Gb function depends on whether connectivity to a 2G access network is required.

To provide redundancy, two Data VMs should be used to connect to the same BSS node. The two

data VMs support the same set of BSS nodes and run in active/active load-sharing redundancy

mode. The two VMs are synchronized with regard to the connectivity information to the BSSs.

Connectivity to the BSS is maintained as long as one of the two VMs is in service.

4.7.2 Subscriber Data

The Subscriber Data (SD) function provides user bearer service on the SGSN. For 3G subscribers, it

acts as a split tunnel that relays user packets from the GGSN to the RNC and vice versa. For 2G

subscribers, it provides additional services. The services include:

Link layer: The SD function supports both acknowledged and unacknowledged LLC layer

between the UE and the SGSN. Additionally, it performs ciphering/de-ciphering based on agreed

ciphering algorithm on the link layer frames.

MME/SGSN Software



21

SNDCP layer: This layer bridges the LLC layer and the IP layer for the UE. The SD function can

provide both header compression and V.42bis data compression at this layer to reduce the data

size over the air.

The SD function is required for the SGSN. It is instantiated on every Data VM unless the data VM is

used for SGSN specific signaling functions below.

4.8 Steering Load Balancer VM

The SLB VM, or LB VM, forwards ingress packets to the 3GPP address of the target VMs. On the

SLB VM, the LBCtrl process programs steering policies into a forwarding infrastructure running within

the SLB VM kernel. This configuration is used to steer incoming traffic to specific target VMs.

Two or more (up to eight) SLB VMs can be instantiated on separate hosts. All policies are

programmed on each SLB VM allowing the ability to load balance ingress 3GPP traffic across all SLB

VMs. Egress traffic is handled on the target VM by routing the packets back to the SLB VM using

multi-path routing (in order to load balance the egress 3GPP traffic). 2G and 3G user data does not

transverse the SLB VM and is routed directly to the target Data VMs with a static route configured in

the next-hop router/L3-capable switch.



22

5 Interfaces

5.1 Supported Interfaces

The vMME supports a plethora of interfaces that make it the most flexible mobility management core

node on the market. It can be deployed as a legacy 2G-only SGSN, 3G only SGSN, a combined

2G/3G SGSN, an S4-based SGSN, a standalone MME (suitable for both current CDMA operators as

well as GPRS/UMTS operators) or a combined 2G/3G/4G MME/SGSN.

In this section, we will discuss the characteristics of each interface supported. The sub-section below

captures the summary of all interfaces while the ensuing sub-sections provide an in-depth look for

each interface.

5.2 Summary

As a combined MME/SGSN, the vMME supports an extensive array of 3GPP defined interfaces as

well as a few value-added proprietary interfaces. The following table provides a condensed view of all

the logical interfaces available on the MME/SGSN. The ensuing sections provide a more detailed

view of each interface.

Table 2. Logical Interfaces

Interface

Name

Peer Node Relay Node Local IP Usage

Name Cardinality Name Cardinality Min Max Type

S1 eNodeB 25000 N/A 1 4 IPv4 and IPv6

S3 SGSN or

MME

1000 N/A 14 2 IPv4 and IPv6

S4 SGW 1000 N/A 1 2 IPv4 and IPv6

S6 HSS 1000 if via

Relay

248 if direct

connect

Diameter

Agent

248 1 20 IPv4 or IPv6

S10 MME 1000 N/A 1 2 IPv4 and IPv6

S11 SGW 1000 N/A 1 2 IPv4 and IPv6

4 The IP addresses of a GTP-C based interface can be shared with other GTP-C interfaces. Thus the minimum

IP consumption for all the interfaces sharing the IP addresses can be 1 in total, instead of 1 for every interface.

Interfaces



23

Interface

Name



S13 EIR 1 Diameter

Agent

248 Shared with S6. IPv4 or IPv6

S16 SGSN 1000 N/A 1 2 IPv4 and IPv6

S101 eAN 15000 N/A 1 2 IPv4 and IPv6

S102 IWS 200 N/A 1 2 IPv4 and IPv6

SBc CBC 4 N/A 1 2 IPv4 or IPv6

SGs VLR 256 N/A 1 2 IPv4 or IPv6

Sv VLR 256 N/A 1 2 IPv4 and IPv6

SLg GMLC 50 DRA 248 Shared with S6. IPv6 and IPv6

SLs eSMLC 20 N/A 1 2 IPv6 or IPv6

Fxa AAA 128 N/A 1 1 IPv4 or IPv6

Ga CGF 2 N/A 1 1 IPv4

Gb BSS

(PCU)

600 N/A 1 15 (GbIP)

IPv4

Gn/Gp

(tunnel)

GGSN 1000 N/A 1 2 IPv4 and IPv6

Gn/Gp

(mobility)

SGSN 1000 N/A 1 2 IPv4 and IPv6

Gn/Gp

(user

bearer)

GGSN No limit N/A 1 15 IPv4

Gd SMS-

GMSC or

SMS-

IWMSC

No limit M3UA

peer

500 1 10 IPv4

Ge SCP 128

Gf EIR 1

Gr HLR 1000

Gs VLR 2565

Iu

(signaling)

RNC 4096 M3UA

peer

8192 1 40 IPv4

Iu (user RNC No limit N/A 1 15 IPv4

5 Shared with the SGs interface for a combined MME/SGSN.

Interfaces



24

Interface

Name



bearer)

NAS UE 4,160,000 Access Node (See Gb,

Iu and S1)

0 0 N/A

X1 LIG ADMF 1 N/A 1 1 IPv4 or IPv6

X2/X3 LIG DF 1 N/A

DNS DNS

Server

8 N/A 1 1 IPv4 or IPv6

5.2.1 S1 Interface

The S1 Interface allows the eNodeBs to communicate with the Evolved Packet Core network. The

interface is split between S1-MME (also referred to as S1-C) for Control plane and S1-U for User

plane. The MME only terminates the S1-MME, whereas the Serving Gateway terminates the S1-U.

The following figure shows the protocol stack for S1-MME.

Figure 5. Protocol Stack for S1 Interface for Control Plane

For the S1 interface, the peer node for the MME is the eNodeB.

The MME allows the operator to configure the version of the S1-AP specification to be used over the

S1 interface. The supported versions of TS36.413 are: V9.5.1, 10.6.0 or 11.8.0. The following table

shows the messages supported for each of the configured versions.

Table 3. S1-AP Messages

S1-AP

SCTP

IP

L2

L1

eNodeB

S1-MME

MME

S1-AP

SCTP

IP

L2

L1

Interfaces



25

# Message Type Message

Direction

V9.5.1/V10.6.0/V11.8.0

1 E-RAB Setup Request eNB MME Supported

3 E-RAB Modify Request eNB MME Supported

5 E-RAB Release Command eNB MME Supported

7 E-RAB Release Indication eNB -> MME Supported

8 Initial Context Setup Request eNB MME Supported

10 Initial Context Setup Failure eNB -> MME Supported

11 UE Context Release Request eNB -> MME Supported

12 UE Context Release Command eNB MME Supported

14 UE Context Modification Request eNB MME Supported

16 UE Context Modification Failure eNB -> MME Supported

17 Handover Required eNB -> MME Supported

18 Handover Command eNB

Interfaces



26


Direction

V9.5.1/V10.6.0/V11.8.0

36 Reset eNB MME Supported

37 Reset Acknowledge eNB MME Supported

38 Error Indication eNB MME Supported

39 S1 Setup Request eNB -> MME Supported

40 S1 Setup Response eNB MME Supported

62 MME Direct Information Transfer eNB MME Supported

64 MME Configuration Transfer eNB MME Not supported

66 Kill Request eNB MME Supported

68 Downlink UE Associated LPPA Transport eNB MME Supported

Interfaces



27


Direction

V9.5.1/V10.6.0/V11.8.0

70 Downlink Non UE Associated LPPA

Transport

eNB MME Supported

At the SCTP layer, the MME supports multi-home function as well as SCTP association recovery

capability required by TS36.412. For the multi-home support, up to two IP addresses are supported at

the local end-point or the remote end-point. The two IP addresses for the same multi-home

association must be of the same IP address type (either IPv4 or IPv6). Mixture of IPv4 address and

IPv6 address for the same SCTP association is not supported. The MME also supports configurable

number of streams for both directions.

At the IP layer, the MME supports both IPv4 and IPv6 addresses at the same time, thus allowing

connectivity to both IPv4 eNodeBs and IPv6 eNodeBs simultaneously. At the minimum consumption,

only a single local IPv4 address is required. At maximum, two local IPv4 addresses and two local

IPv6 addresses are used to support SCTP multi-home to IPv4 eNodeBs and IPv6 eNodeBs.

The maximum number of eNodeBs that the MME can connect to is 25,000 in this release.

5.2.2 S3 Interface

The S3 interface facilitates the UE mobility between an S4-SGSN and an MME. This interface along

with mobility interfaces between the S4 SGSNs (S16), Gn-SGSN (Gn/Gp), and between the MMEs

(S10) is based on the prevalent GTP protocol. For the S-based EPC interfaces, GTPv2 is used. For

the legacy Gn/Gp interface, GTPv1 is used.

Interfaces



28

Figure 6. Protocol Stack for S3 and other Mobility Management interfaces

The peer node for the S3 interface is either the MME if this node is acting as the source or old SGSN,

or the SGSN if this node is acting as the source or the old MME.

The vMME allows the operator to configure the specification version of the GTPv2 to be used over

the S3 interface. The same version is also used for the S10/S16 interfaces. The supported versions

of TS 29.274 on the MME/SGSN are: V9.5.0, V10.10.0 and V11.13.0. The following table shows the

messages supported for each of the configured versions.

Table 4. S3 Interface Messages

# Message Type Message Direction V9.5.0/V10.10.0/V11.13.0

1 Echo Request Source SGSN -> Target MME,

Source MME -> Target SGSN

Supported

2 Echo Response Source SGSN

Interfaces



29

# Message Type Message Direction V9.5.0/V10.10.0/V11.13.0

8 Context Acknowledge Source SGSN Target SGSN

Supported

10 Forward Relocation

Response

Source SGSN Target SGSN

Supported

12 Relocation Cancel

Response

Source SGSN

Interfaces



30

5.2.3 S4 Interface

The S4 interface is used for session management between the S4-SGSN and the SGW. This

interface along with the other session management interfaces between the Gn SGSN and the GGSN

(Gn/Gp) or between the MME and the SGW (S11) is based on the GTP protocol. For the S-based

EPC interfaces, GTPv2 is used. For the legacy Gn/Gp interface, GTPv1 is used.

Figure 7. Protocol stack for S4 interface and other Session Management interfaces

The peer node for the S4 interface is the SGW. The versions supported in this release are TS29.274

V9.5.0 and TS29.274 V10.10.0. The following table shows the messages supported for each of the

configured versions.

Table 5. S4 interface GTP-C Messages

# Message Type Message Direction V9.5.0/V10.10.0

1 Echo Request S-GW SGSN

Supported

2 Echo Response S-GW SGSN

Supported

3 Create Session Request S-GW SGSN Supported

5 Create Bearer Request S-GW -> SGSN Supported

6 Create Bearer Response S-GW

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31

# Message Type Message Direction V9.5.0/V10.10.0

10 Modify Bearer Response S-GW -> SGSN Supported

11 Delete Session Request S-GW SGSN Supported

13 Delete Bearer Request S-GW -> SGSN Supported

14 Delete Bearer Response S-GW SGSN Supported

16 Downlink Data Notification Acknowledge S-GW S-GW Supported

38 Trace Session Deactivation SGSN -> S-GW Supported

39 Change Notification Request S-GW -> SGSN Not supported

40 Change Notification Response SGSN -> S-GW Not supported

41 Delete PDN Connection Set Request SGSN S-GW Not supported

42 Delete PDN Connection Set Response SGSN S-GW Not supported

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At the GTP layer, the vMME supports up to 1000 peers for session (or tunnel) management purpose.

Each peer is represented by a unique IP address of the peer. Path management function is used to

monitor the health and/or reach-ability of the peer node. For the S4 interface, DNS procedures as

defined in TS29.303 are used for the discovery of the peer IP addresses.

At the IP layer, the SGSN supports both IPv4 and IPv6 addresses at the same time, thus allowing

connectivity to both IPv4 SGW and IPv6 SGW at the same time. Up to two local IP addresses (one

IPv4, one IPv6) are needed for the S4 interface. If only IPv4 is used by all the peer nodes, then the

IPv6 address is not required. The local IP addresses can be shared with all other GTP-C based

interfaces.

Figure 8. Protocol stack for S4 user plane interface

The SGSN uses only one local IPv4 address for the purpose. The number of IP addresses that can

be used by the GGSNs is not limited. The following table shows the messages supported.

Table 6. S4 User Bearer Plane Messages

# Message Type Message Direction V9.3.0

1 Echo Request SGSN GGSN Receive only

2 Echo Response SGSN GGSN Supported

3 Error Indication SGSN GGSN Supported

4 Supported Extension Header Notification SGSN GGSN Supported

5 G-PDU SGSN GGSN Supported

GTP-U

UDP

IP

L2

L1

SGSN

S4 user plane

SGW

GTP-U

UDP

IP

L2

L1

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5.2.4 S6 Interface

The S6 interface permits the MME or SGSN to retrieve the Authentication information and

Subscription data from the Home Subscriber Server (HSS). The interface between the MME and the

HSS is referred to as S6a, and the interface between the SGSN and the HSS as S6d. In this

document, S6 is used to refer to both.

The following figure shows the protocol stack used by the S6 interface.

Figure 9. Protocol Stack for S6 interface

The peer node for the S6 interface is the HSS. The vMME can connect directly to the HSS nodes, or

indirectly via a set of Diameter Agents. The vMME has a limitation of 248 direct connected peer

nodes. If all the HSSs are directly connected, then the total number is limited to 248. However, if

Diameter Agents are used, the number of HSSs that can be supported is 1000.

The vMME allows the operator to configure the specification version of the S6 to be used. The

supported versions of TS.29.272 are: V9.5.0 ,V10.7.0 and 11.11.0. The following table shows the

messages supported for each of the configured versions.

Table 7. S6 Messages

# Message Type Message Direction V9.5.0/10.7.0/11.11.0

1 Update Location Request Command HSS MME/SGSN Supported

3 Authentication Information Request Command HSS MME/SGSN Supported

5 Cancel Location Request Command HSS -> MME/SGSN Supported

6 Cancel Location Answer Command HSS MME/SGSN Supported

S6

Diameter

SCTP

L2

L1

MME/SGSN

S6

HSS

S6

Diameter

SCTP

L2

L1

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# Message Type Message Direction V9.5.0/10.7.0/11.11.0

8 Insert Subscriber Data Answer Command HSS MME/SGSN Supported

10 Delete Subscriber Data Answer Command HSS -> MME/SGSN Supported

11 Purge UE Request Command HSS MME/SGSN Supported

13 Reset Request Command HSS -> MME/SGSN Supported

14 Reset Answer Command HSS

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3 Identification Request Old MME New MME Supported

5 Context Request Old MM

Hitachi vMME Product Overview

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